The long awaited Firefox ESR 38 release (38.2.1) is now available after the previous alpha builds in 2015. It took some more time to work on the new fontconfig support and the pango/cairo display engine. The font support and rendering has changed compared to previous versions and thus it requires additional config files and runtime dlls. A newer Cairo version is required for pango, this was ported and is working but printing is currently broken because of this change.
The update to ESR 38.6.1 is already on the way, Mozilla’s next planed update will be ESR 38.7.0.

Firefox 38.2.1 ESR beta for OS/2

Changes in this release:

Switch to original fontconfig for much better font substitution.

Switch from GPI to Pango for better text layout and rendering. This obsoletes ‘gfx.os2.font.*’ properties and also brings long-awaited support for @font-face (loadable Web fonts).

Temporarily disable native print driver support which is currently broken.